Visual cues in the environment such as trees, buildings, objects, terrain textures, and features, plus a cross-check with the flight instruments are necessary for a pilot to adequately assess a helicopter's speed, attitude, altitude, rate of descent, and rate of closure. The lack of visual cues inherent at night in poorly lit areas can make night flying, take-offs, and landings challenging. While the weather conditions were appropriate for VFR flight at night, the dark lighting conditions of the surrounding area and the approach over the dark surface of the lake provided ideal conditions for the black hole illusion. It is likely that as a result of this illusion, the pilot believed the helicopter was higher than it was during the approach to land. The pilot unknowingly flew the helicopter lower than the intended approach path, causing the helicopter to collide with the surface of the water well before reaching the desired landing area. The minimum requirements necessary to obtain a private helicopter pilot night rating may not be sufficient to adequately educate and demonstrate to private helicopter pilots the risks involved in night flying, including visual illusions. Present night rating requirements are the same for private helicopter pilots as for private fixed-wing pilots, yet the environments in which they may operate at night can vary greatly. Flying over the lake on approach at night ensures a helicopter is away from obstacles and allows for a shallower approach to land. However, in the event of an unforeseen problem, the helicopter may not be within gliding distance from the shore, thereby posing a risk to the aircraft and its occupants. It is unlikely that the missing persons would have survived more than a few minutes given the cold water temperatures. Current regulations do not specify light intensity, colour, number of lights, or approach path aids for private helicopter landing pads. The three (of four) low-intensity, solar-powered LED lights on the corners of the landing pad and the bonfire in front of the landing area would not have illuminated the surrounding area sufficiently to help the pilot judge a safe and constant approach angle over the dark, featureless surface of the water.Analysis Visual cues in the environment such as trees, buildings, objects, terrain textures, and features, plus a cross-check with the flight instruments are necessary for a pilot to adequately assess a helicopter's speed, attitude, altitude, rate of descent, and rate of closure. The lack of visual cues inherent at night in poorly lit areas can make night flying, take-offs, and landings challenging. While the weather conditions were appropriate for VFR flight at night, the dark lighting conditions of the surrounding area and the approach over the dark surface of the lake provided ideal conditions for the black hole illusion. It is likely that as a result of this illusion, the pilot believed the helicopter was higher than it was during the approach to land. The pilot unknowingly flew the helicopter lower than the intended approach path, causing the helicopter to collide with the surface of the water well before reaching the desired landing area. The minimum requirements necessary to obtain a private helicopter pilot night rating may not be sufficient to adequately educate and demonstrate to private helicopter pilots the risks involved in night flying, including visual illusions. Present night rating requirements are the same for private helicopter pilots as for private fixed-wing pilots, yet the environments in which they may operate at night can vary greatly. Flying over the lake on approach at night ensures a helicopter is away from obstacles and allows for a shallower approach to land. However, in the event of an unforeseen problem, the helicopter may not be within gliding distance from the shore, thereby posing a risk to the aircraft and its occupants. It is unlikely that the missing persons would have survived more than a few minutes given the cold water temperatures. Current regulations do not specify light intensity, colour, number of lights, or approach path aids for private helicopter landing pads. The three (of four) low-intensity, solar-powered LED lights on the corners of the landing pad and the bonfire in front of the landing area would not have illuminated the surrounding area sufficiently to help the pilot judge a safe and constant approach angle over the dark, featureless surface of the water. It is likely that the effect of the black hole illusion caused the pilot, in full control of the aircraft, to unknowingly fly the helicopter lower than the intended approach path, causing the helicopter to collide with the surface of the water well before reaching the desired landing area. The helicopter approached the landing pad over water and, after colliding with the lake surface, the occupants had to evacuate in near-freezing water temperature, exposing them to hypothermia.Findings as to Causes and Contributing Factors It is likely that the effect of the black hole illusion caused the pilot, in full control of the aircraft, to unknowingly fly the helicopter lower than the intended approach path, causing the helicopter to collide with the surface of the water well before reaching the desired landing area. The helicopter approached the landing pad over water and, after colliding with the lake surface, the occupants had to evacuate in near-freezing water temperature, exposing them to hypothermia. The minimum requirements necessary to obtain a private helicopter pilot night rating may not be sufficient to adequately educate and demonstrate to private helicopter pilots the risks involved in night flying, including visual illusions. Current regulations do not specify light intensity, colour, number of lights, or approach path aids for private helicopter landing pads, thereby increasing the risk of accidents or incidents in degraded environmental conditions.Findings as to Risk The minimum requirements necessary to obtain a private helicopter pilot night rating may not be sufficient to adequately educate and demonstrate to private helicopter pilots the risks involved in night flying, including visual illusions. Current regulations do not specify light intensity, colour, number of lights, or approach path aids for private helicopter landing pads, thereby increasing the risk of accidents or incidents in degraded environmental conditions.